Gunfire control computer



Jul 9, 1946.

w. H. NEWELL Wmau ElhUM /V 0 3 O g! GUNFIRE CONTROL COMPUTER Filed Feb. 19, 1941 2 Sheets-Sheet 1 INVENTOR William lLNeweZl Z572 JAM/- ATTORNEY ?35, REGiSRtHS;

July 9, 1946. w, w 2,403,543

GUNFIRE CONTROL COMPUTER Feb- 19, 2 sheets-sheet 2 PREPARATION PERIOD.

TARGET SPEED RANGE BALLISTIC COMPUTER SIGHT ANGLE INVENTOR g n y'lbiamz/glllvewew l f A) W E? i M ATTORNEY- LOU: EURO l EH6).

@EQBME MUM Patented July 9, 1 946 GUNFIRE CONTROL COIWPUTER William H. Newell, New York, N. Y., assignor to Ford Instrument Company, Inc., Long Island City, N. Y., a corporation of New York Application February 19, 1941, Serial No. 379,632

7 Claims. (Cl. 235-615) This invention relates to gun-fire control computers and particularly to that typeof computers used to control the firing of guns against aircraft.

The problem of the control of gun-fire against aircraft may be divided into two classes; (1) Where the aircraft or target is approaching directly towards its objective or the point of observation and the firing gun, and (2) where the target is passing at a distance to one side or the other of the observing and firing point. The invention herein disclosed is applied to the first mentioned class. It will of course be understood that some of the principles thereof are applicable to the solution of problems of the second mentioned class.

In considering the solution of the problem of anti-aircraft fire control to which this invention is applied as one embodiment thereof, it is assumed that the target is directly approaching its objective, which is the point of observation and the point of firing of the gun, at a substantially constant height above the horizontal plane of the objective, such as would be done in horizontalbombing of a selected point. Upon the picking up of the target by observers at the objective, the slant range of the target and its elevation above the horizontal, expressed in angular units, are observed by instruments well known in the art and from the observed data the height of the target and the horizontal range may be determined, or if the height of the target is known or obtained by observations and the elevation is observed, the slant range and the horizontal range may be determined.

From experimental data obtained during target practices, the most effective ranges of the guns are known as well as the time in seconds required to set and adjust the sights and the fuses of the projectiles and to load and fire the projectiles. In this specification, the time required to set the observed values into the mechanisms, for the mechanisms to calculate the advance range or fuse setting and the sight angle, and the time required to adjust the sight and gun and load'and fire the gun is defined as the preparation period of time. This preparation period is arbitrarily selected and is based upon experience under various circumstances of operation.

The object of the invention is to provide a mechanism settable in accordance with an observed range or height and elevation of an appreaching aircraft target and settable in accordance with the speed of the target and the selected preparation period of time following the instant of the observations, for computing the sight angle or difference in elevation of the gun and the line of sight at the instant of firing and the timesetting values of the fuses of the fired projectiles.

Mechanisms for accomplishing the objects of the invention and their operation will be understood by considering the following description and accompanying drawings in which:

Fig. 1 is an elevation side view of an aircraft target directly approaching an observing and firing point at a constant height and showing the consecutive angular and linear relations of the target to the observing and firing point; and

Fig. 2 is a diagrammatic view of a mechanism to compute the values required in the control of the fire of the gun.

Referring particularly to Fig. 1, an aircraft or target I is directly approaching the observ ing and firing point 0 at a constant height (H) above the horizontal OO' and at a horizontal speed of St.

When the target I reaches point A, observers at O observe the slant range (R) and the elevation angle of the target (Al from which the height (H) and the horizontal range (RH) may be calculated by the equations resulting from the right angle triangle 0AA of H=R sin A1 and RH =R cos A1, respectively. A is the projection of the point A on the horizontal 0-0. g

The preparation period of time (X) is selected as required and added to the time of flight (t) of the projectile as obtained from ballistic tables or curves and the sum is multiplied by the speed of the target (St) to give the distance traveled by the target during the time (X +t) represented by the line AC, thus defining the intercept point C at which the target will be at the end of the time of flight period. The value of AC may be expressed by the equation AC=(X+t) St (1) The horizontal range of the target I at point C (RHZ) is equal to the observed horizontal range minus the distance AC or RH2=RH (X+t) St (2) or A2 tan m The travel of the target during the time of flight is equal to the speed of the target multiplied by the time of flight or t-St and is indicated on Fig. 1 by the line BC, or

BC=t-St (5) This distance determines the point B or the position of the target at the time the gun is fired. It is obvious that B represents the horizontal range to the firing point (EH3) and that The elevation angle of the firing point (A3) is obtained from the right angle triangle 03B and is the angle whose tangent is the height divided by the horizontal range to the firing point (RH3) A3=tan (7) The elevation of the gun above the line of sight to the point B, to allow for the movement of the target during the time of flight is known as vertical angular deflection (Ut) and may be expressed as Ut=A2--A3 (8) Referring particularly to Fig. 2, the vector analyzer or component solver 2 includes a disk 3 with a radial range scale 4 and index 5 engraved thereon. The disk 3 is rotated about its axis by gears 6 turned by shaft 1 to positions representing angles of elevation of the target I. Index 5 cooperating with scale 8 indicates the angular setting of disk 3.

Movable at right angles to each other and in suitable guides are slides 9 and III each of which carries a stiff wire, I I and I2 respectively, mounted to extend perpendicular to the direction of movement of its respective slide. Cross wire I2 cooperates with scale I3 to visually indicate the height (H) of the target represented by the relative position of slide I0 and the position of wire II relative to the center of disk 3 indicates the horizontal range represented by the position of the slide 9.

After setting the preparation period of time (X) and the target speed (St), as will be hereinafter described, the disk 3 is rotated by handle I4 turning shaft 1 until the index 5 is opposite the observed elevation of the target (AI). Slide III is moved by handle I5, shaft I6 and gears I'I until wire I2 crosses range scale 4 at the observed slant range (R). Slide 9 is moved by handle I8, shaft I9, through differential 20 and by shaft 2| and gears 22 until wire I I intersects the range scale 4 at the observed slant range (R). The positions of slide 9 and shaft 2| therefore represent the observed-instant horizontal range (RH) of the target and the positions of the slide I0 and shaft I6 represent the height of the target (H). The position of shaft I 9 represents the horizontal range (RH2).

The length of the preparation period. of time 4 (X) is set into the conventional multiplier 23 by crank 24, shaft 25, clutch 26, shaft 21, shaft 28, differential 29 and shaft 30. Target speed (St) is determined from observation or otherwise and set into multiplier 23 by crank 3| and shaft 32. The values of X and St thus set into the multiplier 23 are made visually available by dials 33 and 34 geared, respectively, to shafts 28 and 32.

The value of the time of flight period (t), represented by the rotation of shaft 38 is set into multiplier 23 by connecting shaft 38 to the third side of differential 29 where it is combined with the preparation period of time (X) from shaft 28, so that the output shaft 39 of multiplier 23 represents the line A--C of Fig. 1, or the change in horizontal range during the preparation period and the time of flight period as shown in Equation 1. The mechanism for generating the value of t will be described hereinafter.

It will be seen from Equation 3, that, having set the selected value of preparation period (X) by crank 24 and the observed value of target speed (St) by crank 3| so the resultant position of output shaft 39 of multiplier 23 represents the distance AC or (X-I-t) St, the position of shaft I9 as set by handle I8 will represent the horizontal range (EH2) when the wire II is brought to intersect the range scale 4 at the point representing slant range (R).

The value of the period of time of flight of the projectile is obtained by connecting shaft III, the position of which represents horizontal range (RH2), and shaft I6, the position of which represents height (H), to a conventional three-dimensional cam unit or ballistic computer.

The cam 40 of this unit consists of a solid rotated by the shaft I9 representing horizontal range (RH2). The surfaces of the various lateral cross-sections of the solid along its axis form a cam surface to give to cam follower 4| a motion proportional to the time of flight of the projectile for the range represented by the rotational position of the cam and the value of height represented by the axial position of the follower 4|. The cam follower 4| is positioned parallel to the axis of the cam 40 to engage the various lateral sections of the solid cam in accordance with the value of height (H), as represented by rotational position of the threaded portions of shaft l6, which engages the threaded carriage 4Ia on which follower 4| is mounted for rotational movement. Cam follower 4| is kept in engagement with the cam surface by spring 42 and its motion is transmitted to elongated gear 43 on shaft 38 by the toothed sector 44 to which follower 4| is secured. Shaft 38 is connected to differential 29 to introduce time of flight into multiplier 23 as previously described.

It will be seen, as shaft I9 is turned by handle I8 to bring the range wire II of vector analyzer 2 to its proper intersecting point for the observed values of range and elevation, that the connection of shaft I9 to the cam 40 will modify the time of flight input to multiplier 23 and in consequence, the output shaft 39 will be moved to additionally move the shaft 2| and the range wire I I, that is, the movement of shaft I9 has a direct effect on the position of wire II through differential 20, and an indirect effect through cam 40, follower 4|, sector 44, gear 43, shaft 38, differential 29, shaft 30, multiplier 23, shaft 39 and differential 20.

The clutch 26 is actuated by a lever 45 and is normally held in a closed position by the spring sits bgd'fgli nous 46. The gear 41 is mounted on shaft 35 and driven by gear 36 on shaft. 28. A spring 48 around shaft 35 is secured at one end to gear 41 and the other end to the frame of the instrument. A stop pin 49 is mounted on gear 41 and a cooperating stop pin 50 is secured to the frame of the instrument. The gear 41 is so set relative to the shaft 28 that when the dial 33 is at zero the pin 49 is against the fixed stop p 50 n h spring 48 is under initial tension tending to hold the stop pins in engagement. As the setting is made to introduce the predetermined value of the preparation period of time the gear 41 is rotated to move stop pin 49 away from the fixed pin 56 and the tension of spring 46 is increased.

When the previously described settings have been made the preparation period of time (X) is removed from multiplier 23 by moving lever 45 against the tension of spring 46 thereby opening clutch 26. This permits gear 41 to be rotated backwards under the force of spring 48, until stop pin 49 on gear 41 comes up against stop pin 50 mounted on the frame of the instrument, when dial 33 and shaft 28 are returned to their zero positions.

When the shaft 28 is returned to represent zero value of the preparation period (X), it will be seen that the input movement to multiplier 23 by shaft 36 is equal to time of flight (it) alone and therefore the resulting position of output shaft 39 represents target speed multiplied by time of flight (t-St).

As shaft I9 is held by the handle 18 at the previously determined value of horizontal range (RH2)' and shaft 39 now presents t-St or the distance BC of Fig. 1, the position of shaft 2|, slide 9 and range wire I I, determined by the connections to shafts l9 and 39 through differential 20, now represents RH 2+t-St which equals horizontal range (RH3) (see Equation 6).

With slide 9 and Wire i l (shown in dotted line) now moved to the left to the position corresponding to horizontal range (EH3), disk 3 is turned to the left by handle l4 and shaft 1 until the radial line of the range scale 4 is directly opposite the intersection of wire ll (dotted position) and wire 12. In this position the rotational position of disk 3 and shaft 1 represent the elevation of the target at point B (A3), as shown by Equation 7.

With shaft l9 still held in the position representing the value of horizontal range (RHZ) slide 5| of vector solver 52 is also in a position representing EH2. The other input to vector solver 52 is slide 53 which is set in position by shaft l6 to represent height (H). The position of the output of vector solver 52, shaft 54, therefore represents the elevation of the target at point C or elevation (A2), as shown by Equation 4.

The movements of shafts 1 and 54 are combined by differential 55 to obtain the value of the change of the elevation angle due to movement of the target during the time of flight, which value is represented by the resulting rotational position of shaft 56, the output of differential 55. This value is generally known as vertical deflection due to movement of the target during the time of flight (Ut) as shown by Equation 8.

The value of super elevation (e) is obtained by a three-dimensional cam 51 which is in all respects in construction and operation similar to cam 49, except that the surface of the solid is such that for the inputs of height (shaft I6) and horizontal range (shaft I9) the movement of cam follower 58, toothed sector 59, elongated gear 66 tion (e).

As the sight angle (Us) from Equation 9 is equal to the sum of the elevation angle (Ut) and the super elevation (e) the movements of shafts 56 and 6| are combined in differential 62, the output of which is transmitted to visual dial 63 by shaft 64 and gear 65. Corrections may be applied to the sight angle by moving ring dial 66, which is mounted coaxially with dial 63 and has an index thereon cooperating with the scale on dial 63. Movement of dial 66 is had by moving handle 61 on shaft 68 which is geared to dial 66.

Values of deflection (Ds) clue to drift which are proportional to the super elevation (e) are made visually available by dial 69 which is geared to shaft 6|. Corrections to deflection may be added by moving ring dial 10 which is mounted coaxially with dial 69 and has an index thereon cooperating with thescale of dia1 69. Dial, 19 is moved by crank H on shaft 12, which is geared to dial 10.

The values for determining the fuse settings are made visually available by connecting fuse dia1 13 to shaft 38, the position of which represents time of flight (t), by shaft 14. Corrections to fuse settings may be added by moving ring dial 15 mounted coaxially with dia1 13 and with an index and scale thereon cooperating with the scale of dial l3. Dial I5 is moved by crank 16 on shaft 11, which is geared to dial I5.

It is obvious that various changes may be made by those skilled in the art in the details of the invention as disclosed in the drawings and described above within the principle and scope of the invention as expressed in the appended claims. I

I claim:

1. Apparatus for use in the aiming of a gun for firing a projectile at a target approaching at a co nstan t height above a horizontal plane, comprising a vector analyzer having a range scale angularly settable in accordance with the elevation of the target at an observing instant and including a first slide settable relative to the range scale to positions in accordance with the corresponding horizontal range of the target and a second slide settable relative to the range scale to positions in accordance with the corresponding height of the target, means settable in accordance with a selected preparation period of time, means movable in accordance with the time of flight of the projectile, a first differential for combining the movements of the preparation period settable means and the time of flight movable means, a multiplier connected to the output of the first differential and also settable in accordance with the speed of the target, means settable to represent the horizontal range at the end of the time of flight, a second differential actuated by the output of the multiplier and the range settable means and connected to position the first slide, ballistic computing means, having input members connected to the range settable means and to the said second slide, said ballistic computing means including an output moved in proportion to the time of flight, and motion transmitting means connecting the output of the ballistic computing means and the time of flight movable means, whereby the output of the multiplier represents change in horizontal range of the target during the preparation period and the time of flight.

2. Apparatus for use in the aiming of a gun for firing a projectile at a target approaching at a constant height above a horizontal plane, comprising a vector analyzer having a range scale angularly settable in accordance with the elevation of the target at an observing instant and including a first slide settable relative to the range scale to positions in accordance with the corresponding horizontal range of the target and a second slide settable relative to the range scale to positions in accordance with the corresponding height of the target, means settable in accordance with a selected preparation period of time including a zero setting stop, means movable in accordance with the time of flight of the projectile, a first differential for combining the movements of the preparation period settable means and the time of flight movable means, a multiplier connected to the output of the first differential and also settable in accordance with the speed of the target, means settable to represent the horizontal range at the end of the time of flight, a second differential actuated by the output of the multi plier and the range settable means and connected to position the first slide, ballistic computing means having input members connected to the range settable means and to the said second slide, said ballistic computing means including an output moved in proportion to the time of flight,

motion transmitting means connecting the output of the ballistic computing means and the time of flight movable means, resilient means connected to the preparation period movable means for moving the said movable means to the said zero setting stop and releasable setting means for adjusting the preparation period movable means.

3. Apparatus for use in the aiming of a gun for firing a projectile at a target approaching at a constant height above a horizontal plane, comprising a vector analyzer having a range scale angularly settable in accordance with the elevation of the target at an observing instant and including a first slide settable relative to the range scale to positions in accordance with the corresponding horizontal range of the target and a second slide settable relative to the range scale to positions in accordance with the corresponding height of the target, means for angularly setting the range scale, means settable in accordance with a selected preparation period of time including a zero setting stop, means movable in accordance with the time of flight of the projectile. a first difierential for combining the movements of the preparation period settable means and the time of flight movable means, a multiplier connected to the output of the first differential and also settable in accordance with the speed of the target, means settable to represent the horizontal range at the end of the time of flight, a second differential actuated by the output of the multiplier and the range settable means and connected to position the first slide, ballistic computing means having input members connected to the range settable means and to the said second slide, said ballistic computing means including an output moved in proportion to the time of flight, motion transmitting means connecting the output of the ballistic computing means and the time of flight movable means, resilient means connected to the preparation period settable means for moving the said settable means to the said zero setting stop, releasable setting means for adjusting the preparation period movable means, a vector solver having two component members connected to the said second slide and to the range settable means respectively, a third 8 differential connected to the range scale angular setting means of the vector analyzer and to the output of the vector solver, a second ballistic computing means having input members connected to the range settable means and to the said second slide, said second ballistic computing means including an output moved in proportion to the super elevation, and a fourth differential connected to the output of the third differential and to the output of the second ballistic computing means whereby the output of the fourth differential represents the sight angle of the gun when the resilient means is released to return the preparation period settable means to its zero setting stop and the range scale angular setting means is adjusted to bring the range scale into correspondence with the position of the second slide and the resulting position of the first slide.

4. In apparatus for use in the aiming of guns, a vector analyzer having a graduated range scale angularly settable to represent the position of Margret, means for initially setting said scale in accordance with the observed angular relation of the target from an observing station, a pair of com nenirrrrembersassociated with said scale, means for setting one of said component members in accordance with the height of the target corresponding to thegmtion o'fsaid range scale representing the observed range of the target, means for partly setting the second of said component members in accordance with the present horizontal range corresponding to the graduation of said range scale representing the observed range of the target, means for additionally setting the second of said component members in accordance with the output of a multiplying mechanism having two input members, means for actuating one of said input members in accordance with the target speed, means for actuating the other of said input elements in accordance with the time of flight of the projectile and a selected time interval, means for eliminating the effect of the selected time interval on the multiplier, whereby the said second component member is moved to represent the horizontal range at the termination of the selected time interval, a vector solver having one component input directly actuated by the means for partly setting the second of said component members in accordance with the present horizontal range and a second component input actuated by the means for setting one of said component members in accordance with the height and having a vector member angularly positioned in accordance with the setting of the said component inputs, means for combining the resulting angular position of the vector member with the means for angularly setting the first mentioned vector, whereby the output of the combining means represents the angular movement of the target during the time of flight when the vector range scale is set in accordance with the intersection of its associated component members after the elimination of the effect of the selected time interval.

5. In apparatus for use in the aiming of guns, a vector analyzer having a graduated range scale angularly settable to represent the position of a target, means for initially setting said scale in accordance with the observed angular relation of the target from an observing station, a pair of component members associated with said scale, means for setting one of said component members in accordance with the height of the target corresponding to the graduation of said range scale representing the observed range of the LOU! HLUO I Lllun secret. tics target, means for partly setting the second of component members in accordance with the present horizontal range corresponding to the graduation of said range scale representing the observed range of the target, means for additionally setting the second of said component members in accordance with the output of a multiplying mechanism having two input members, means for actuating one of said input members in accordance with the target speed, means for actuating the other of said input elements in accordance with the time of flight of the projectile and a selected time interval, means for eliminating the eflect of the selected time interval on the multiplier, whereby the said second component member is moved to represent the horizontal range at the termination of the selected time interval, a vector solver having one component input directly actuated by the means for partly setting the second of said component members in accordance with the present horizontal range value and a second component input actuated by the means for setting one of said component members in accordance with the height and having a vector member angularly positioned in accordance with the set ting of the said component inputs, means for combining the resulting angular position of the vector member with the means for angularly setting the first mentioned vector, whereby the output of the combining means represents the angular movement of the target during the time of flight when the vector range scale is set in accordance with the intersection of its associated component members after the elimination of the effect of the selected time interval, ballistic computing means settable by the means for setting one of said component members in accordance with the height and by the means for partly setting the second of said component members in accordance with the present horizontal range value including output means moved in proportion to the time of flight of the projectil and the super elevation respectively, means for transmitting the time of flight output means of the ballistic computing means to the multiplying mechanism, and means for combining the super elevation output of the ballistic computing means with the output of the last mentioned combining means whereby a part is positioned to represent the sight angle.

6. Apparatus for use in the aiming of a gun for firing a projectile at a target approaching at a constant height above a horizontal plane, comprising a vector analyzer having a range scale angularly settable in accordance with the elevation of the target at an observing instant and including a first slide settable to positions in accordance with the horizontal range of the target and a second slide settable to positions in accordance with the height of the target, means settable in accordance with a preparation period of time including a zero setting stop, means movable in accordance with the time of flight of the projectile, differential means for combining the movement of the preparation period means and the time of flight means, means settable in accordance with the rate of movement of the target, multiplying means actuated by the differential means and the rate settable means, means settable to represent the horizontal range of the target at the end of the time of flight, combining means actuated by the multiplying means and the range settable means and connected to position the first slide, whereby the position of the first slide indicates the horizontal range of the target at the observing time, and means for selectively moving the preparation period settable means to engage the zero setting stop, whereby the effect of said preparation period settable means on the multiplier is removed and the first slide is positioned to indicate the horizontal range at the instant of firing.

7. Apparatus for use in the aiming of a gun for firing a projectile at a target approaching at a constant height above a horizontal plane, comprising a vector analyzer having a range scale angularly settable in accordance with the elevation of the target at an observing instant and including a first slide settable to positions in accordance with the horizontal range of the target and a second slide settable to positions in accordance with the height of the target, means settable in accordance with a preparation period of time including a zero setting stop, means movable in accordance with the time of flight of the projectile, differential means for combining the movement of the preparation period means and the time of flight means, means settable in accordance with the rate of movement of the target, multiplying means actuated by the differential means and the rate settable means, means settable to represent the horizontal range of the target at the end of the time of flight, combining means actuated by the multiplying means and the range settable means and connected to position the first slide, whereby the position of the first slide indicates the horizontal range of the target at the observing time, ballistic computing means having input members connected to the means settable to represent the horizontal range of the target at the end'of the time of flight and to the second slide, said ballistic computing means including an output moved in proportion to the time of flight, motion transmitting means connecting the output of the ballistic computing means to the time of flight movable means, and means for selectively moving the preparation period settable means to engage the zero setting stop, whereby the effect of said preparation period settable means on the multiplier is removed and the first slide is positioned to I indicate the horizontal range at the instant of firing.

WILLIAM H. NEWELL. 

